Video is important in the field of security and surveillance. Video is often handled in digital form. This offers many advantages over analog video. Analog video is typically digitized and compressed by a dedicated hardware device called an encoder. The encoder generates a digital video stream that has been compressed in one of many digital video compression formats such as MPEG2, MPEG4 and MJPEG, and H.264. The encoder also provides an interface to a standard data network such as Gigabit Ethernet and transmits the video using one of many standard network protocols such as TCP/IP or UDP. Other application layer protocols can be used on top of TCP such as HTTP and RTP to assist in the delivery of digital video to other devices connected to the network.
There are several advantages that are gained by converting the video to digital form that can be transmitted over standard video networks. Scaling of the number of video sources is no longer an issue because an arbitrary number of sources can be handled. Standard network switches can be added for more network connections. The nature of IP switching and routing allows this scaling to work easily and smoothly. The digital data network allows the video to be transmitted over any distance. The data network also acts as a switching system. Digital video sources may be switched to any destination connected to the network. With IP networks, the switching is packet based, but modem IP networks are easily able to switch real-time streams of digital video between any source and any destination as long as there is no congestion encountered along the way and the needed paths through the network have sufficient bandwidth for the streams.
However, some client devices are still required to transcode the encoded digital video stream from the camera from one compression format to another digital video compression format compatible with a video player at the client device. Such a transcoding process consumes limited resources available at the client device. Even after transcoding, the client device may still require frames to be dropped or the image to be resized because of device and bandwidth limitations.